135 



rlaf'tylus wanting. (Tiiathopotla comparatively feeble in structure, jjropodns 

 of the anterior ones simple, without any distinctly defined palmar edge, that 

 of the posterior ones forming, at the tip, a minute chela. The 2 anterior pairs 

 of pereiopoda comparatively robiist, carpal joint having, posteriorly, a rounded 

 lamellar expansion, propodal joint constricted at the base, outer part obtusely 

 rounded. The 3 posterior pairs of pereiopoda very largely developed, with 

 the basal, meral and carpal joints expanded to scale-like pieces, flanking the 

 sides of the animal. Dactylus wanting in all the pereiopoda. Pleopoda 

 pooi'ly developed. Uropoda rather dissimilar in structure, 1st pair compara- 

 tively strong, with both rami coarsel}' spinous at the truncated tips; 2nd 

 pair much smaller, with the rami setous; last pair with the rami slender 

 linear, the outer biarticulate, and longer than the inner, both setous at the 

 tip. Telson forming a broad ])late slightly incised in the middle. 



Remarlcs. — Of the several names assigned to tliis genus, that of 

 Haustorius proposed by Statius Miiller is by far the oldest, and should there- 

 fore, as pointed out by the Jlev. Mr. Stebbing, according to the laws of 

 ])riority, be preferred, though its adjective termination would seem to be less 

 appropriate. Boeck referred the genus to his subfamily Fhoxince, and Dr. 

 Bovallius has subsequently projiosed for its reception a new subfamily Ftery- 

 gocerinn. In my opinion it should more properly be referred to the Ponto- 

 poreiid(r\ exhiliiting, as it does, several points of evident agreement on the one 

 side with sucli true Pontoporeiidse as the genus PrisciJJa, on the other with 

 the genus Urofhoe, now generally referred to the same family. The genus 

 compi'ises, as yet, but a single species, though it may perhaps be questioned 

 whether the Lepidnctyraii dytixCKS of Say is the same species as the European 

 form here described. 



9. Haustorius arenarius, (Slabber). 



(I'l 40). 

 OniscHS arenarius, Slabber, Natuurkundige Verlustigingen etc. p. 92, PL 11, fig. 3 — 4. 



Body very tumid, with Ijroadly vaulted back. Cephalon about the 

 length of the iirst 2 segments of mesosome combined, much depressed in its 

 anterior part, rostral projection short triangular, lateral corners lying nearly 

 in the same plan as the former, acute. The 4 anterior pairs of coxal plates 

 considerably deeper than the body and successively increasing in size posteriorly; 

 4th jmir subtruncated at the tip and very slightly emarginated posteriorly; 

 otli pair almost twice as broad as it is deep ; 6th pair oblique, with the posterior 

 lolie considerably deeper than the anterior. Last segment of metasome much 

 larger than the other two, and flattened above, epimeral plates rounded, with 



